The present invention relates to an apparatus for the production of molten metal by self reduction of agglomerates having oxides of the metal. This includes the production of molten iron, including pig iron and cast iron, as well as metal alloys.
Direct self reduction, and melting and refining processes are generously intended to either produce steel directly from iron ore, make a product equivalent to blast furnace pig iron for use in conventional steel making processes, or produce low-carbon iron as a melting stock for producing steel by conventional processes. These processes are generally intended to supplant blast furnaces as a source of molten iron for steel making.
Blast furnaces typically constitute a cylindrical tower wherein a charge comprising iron ore, pellets, or agglomerates, together with coke and limestone, are sequentially charged through the top of the furnace to form a continuous column of charge material. In the lower portion of the furnace, atmospheric air, which may be preheated, is introduced to the charge. When the charge materials come into contact with hot gases that are ascending from the hearth, the coke is preheated by these gases so that when it reaches the lower portion of the furnace and comes into contact with the air introduced thereto, it will be caused to burn. At the resulting high temperatures existing at this location of the furnace, carbon dioxide is not stable and reacts immediately with carbon to form carbon monoxide. This reaction is not only the main source of heat for the smelting operation, but it also produces a reducing gas (CO) that ascends through the furnace where it preheats and reduces the iron oxide in the charge as it descends through the furnace.
The production capacity of a blast furnace is a function of the internal volume or area and the furnace design parameters for a given production capacity. Consequently, to increase capacity requires increasing the size of the blast furnace and accordingly adjusting design parameters.
The present invention relates to a modular apparatus for producing molten metal, such as molten iron and molten metal alloys by self reduction of agglomerates of metal oxides or melting and refining of prereduced metal. There is provided a plurality of connected cells of identical size and construction that form this modular apparatus. Each cell is connected to a common means for supplying the agglomerates for self reduction or for melting and refining. Each reduction chamber or melting chamber is configured to produce molten metal of like composition by self reduction of the agglomerates under like reduction conditions or melting and refining of the agglomerates supplied to each of the reduction chambers or melting chambers, respectively. The agglomerates may contain either one or both of a reductant and a fluxing agent.
The like reduction or melting and refining conditions include temperature and feed rate of the agglomerates.
Each of the cells includes an identical preheating zone above the reduction chamber or melting and refining chamber through which the agglomerates are introduced and preheated prior to entering the chamber for the self reduction or melting and refining thereof.
Means are provided between the chamber and the preheating zone to direct and evenly distribute off gas from the self reduction or melting and refining through the agglomerates within the preheating zone. Means are additionally provided adjacent the preheating zone for burning combustible off gas from the self reduction or melting and refining to heat the agglomerates within the preheating zone.
The connected cells constitute a self reduction apparatus or melting and refining apparatus of modular or unit construction. Consequently, with the apparatus being divided into modules or unit fractions, each representing the entire equipment, allows the development and design of new furnaces on a one-to-one scale and further allows the performance of tests of different raw materials for changes in production capacity in a modular fashion.